Feb.7 (GMM) The FW35 is yet to see the light of day, but it will almost certainly feature a 'vanity panel' rather than a stepped nose.

Alone amongst the rest of this year's field, Williams has delayed the debut of its 2013 car until Barcelona later this month, choosing instead to run with last year's car at Jerez.

But already up and running is the tweaked 2013 livery, while the 2012-specification FW34 also appeared noticeably different for another reason in Pastor Maldonado's hands on Wednesday.

Brazil's Globo pointed out that the FW34 was fitted with a smooth nose, unlike the unseemly 'step' that featured throughout last year's championship.

This year, the FIA is allowing teams to use a 'vanity panel' to conceal the regulated height difference between the monocoque and nosecone, but some teams - notably Lotus and Caterham - have opted to keep the stepped feature.